Commit c9571721 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: VMX: Drop unnecessary PI logic to handle impossible conditions 



Drop sanity checks on the validity of the previous pCPU when handling
vCPU block/unlock for posted interrupts.  The intention behind the sanity
checks is to avoid memory corruption in case of a race or incorrect locking,
but the code has been stable for a few years now and the checks get in
the way of eliminating kvm_vcpu.pre_cpu.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-23-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 057aa61b

arch/x86/kvm/vmx/posted_intr.c

+10 −14
Original line number Diff line number Diff line
@@ -123,13 +123,11 @@ static void __pi_post_block(struct kvm_vcpu *vcpu) 
	} while (cmpxchg64(&pi_desc->control, old.control,

			   new.control) != old.control);



	if (!WARN_ON_ONCE(vcpu->pre_pcpu == -1)) {

	spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));

	list_del(&vcpu->blocked_vcpu_list);

	spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));

	vcpu->pre_pcpu = -1;

}

}



/*

 * This routine does the following things for vCPU which is going
@@ -156,14 +154,12 @@ int pi_pre_block(struct kvm_vcpu *vcpu) 


	WARN_ON(irqs_disabled());

	local_irq_disable();

	if (!WARN_ON_ONCE(vcpu->pre_pcpu != -1)) {



	vcpu->pre_pcpu = vcpu->cpu;

	spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));

	list_add_tail(&vcpu->blocked_vcpu_list,

			      &per_cpu(blocked_vcpu_on_cpu,

				       vcpu->pre_pcpu));

		      &per_cpu(blocked_vcpu_on_cpu, vcpu->pre_pcpu));

	spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));

	}



	do {

		old.control = new.control = pi_desc->control;